My U.S. Pat. No. 6,706,549 B1 entitled MULTI-FUNCTIONAL MICRO ELECTROMECHANICAL DEVICES AND METHOD OF BULK MANUFACTURING SAME discloses and claims a method of bulk manufacturing SiC sensors, including pressure sensors and accelerometers.
My U.S. Pat. No. 6,845,664 B1 entitled MEMS DIRECT CHIP ATTACH PACKAGING METHODOLOGIES AND APPARATUSES FOR HARSH ENVIRONMENTS discloses methods of bulk manufacturing high temperature sensor sub-assembly packages.
I am a named inventor of U.S. Pat. No. 5,637,905 to Carr et al. and it discloses a high temperature pressure and displacement microsensor made from a Si substrate. A first coil structure is positioned within a recess in the Si substrate. A pressure diaphragm is glass bonded about its periphery to the rim of the recess in the semiconductor substrate. A second coil structure is positioned on the underside of the pressure diaphragm and is electrically isolated from the first coil structure. The coils are inductively coupled together and provide an output indicative of changes in the coupling between the coils.
My U.S. Pat. No. 6,248,646 discloses a process for making an array of SiC wafers on standard larger industry sized wafers. This patent discusses the operating conditions for SiC and SiC-On-Insulator technology and cites the need for sensors and other devices made from SiC.
U.S. Pat. No. 6,883,774 B2 to Nielsen et al. entitled Microelectromechanical High Pressure Microvalve discloses first and second layers of SiC or Si, a stainless steel diaphragm member and switching means. The microvalve is designed for high pressure applications and employs a thin metallic diaphragm sandwiched between first and second layers of SiC or Si. The cracking pressure at which the stainless steel diaphragm opens is approximately 800 psi and the microvalve may be modified to open at pressures from 800-1200 psi. The diaphragm is biased in the closed position and moves from the closed position to the open position when the pressure of fluid in the inlet reaches a preset value. The switching means is connected to the valve body for moving the diaphragm to the closed position against pressure of the fluid in the inlet to the valve. “A recess or cavity 50 in the valve body 26 is provided to allow the diaphragm 16, specifically the central portion thereof, to flex upward, away from valve seat 30a. With the preferred embodiment of microvalve 10, a sloped “dome” is ablated in the underside of the top SiC or Si wafer in order to provide a gentle valve stop. This extends valve life by reducing stress concentrations on the valve diaphragm 16. The smooth sloped edges of the recess provide a gentle stop and prevent rupturing the thin diaphragm of the valve.” See, col. 3, lines 54 et seq. of the '774 patent. A laser is used to form the contours of the underside of the top SiC or Si wafer by ablating the SiC or Si. A shape memory alloy actuator, a piezoelectric actuator, a microsolenoid actuator, or an electromagnetic actuator may be used. The disclosure of the '774 patent indicates and recites “switching means” and movement of the diaphragm from the closed position to the open position. The '774 patent describes a relief valve.
U.S. Pat. No. 6,774,337 B2 to Claydon et al. entitled Method For Protecting The Diaphragm And Extending The Life Of SiC And/Or Si MEMS Microvalves discloses a microvalve and method of forming a diaphragm stop for a microvalve. Much of the disclosure of the '337 patent is similar to the disclosure of the '774 patent but the claimed subject matter differs. United States Patent Application Publication No. US 2005/0098749 A1 is a divisional of the '337 patent and discloses in the proposed claims that the second layer defines a contoured, sloped recess above a central portion of the diaphragm to receive the diaphragm when the diaphragm moves from the closed position to the open position.
U.S. Pat. No. 6,557,820 B2 to Wetzel discloses a pre-stressed diaphragm sandwiched between the upper and lower main bodies in a two-stage valve. The valving arrangement is used to control pressure supplied to the top side of the diaphragm which in turn actuates the principal valve.
U.S. Pat. No. 6,592,098 B2 to Kao discloses a microvalve employing a diaphragm controlled by an electrostatic external actuator device. Both the valve seat and the valve can be comprised of Si.
U.S. Pat. No. 6,126,140 to Johnson et al. discloses electrically conductive polysilicon diaphragms which are corrugated on the periphery thereof. See, col. 2, lines 19-22 of the '140 patent. A three wire system is employed to move the diaphragm toward the open or closed direction.
U.S. Pat. No. 5,452,878 to Gravesen et al. entitled Miniature Actuating Device discloses a diaphragm etched in a substrate, a carrier, and an insulator between the carrier and the diaphragm. An electrostatic field is produced between the carrier and the diaphragm to open and close the device.
U.S. Pat. No. 5,209,118 to Jerman entitled Semiconductor Transducer Or Actuator Utilizing Corrugated Supports discloses a semiconductor deflecting member having vertical travel which is a linear function of applied force. Capacitive plates are used to measure the movement of the deflecting member.
There is growing demand for improved efficient management of energy consumption in jet engines and automobiles. Global reduction of undesirable emissions of hydrocarbons and other combustion by-products such as oxides of nitrogen and carbon monoxide is being sought assiduously. Semiconductor based devices and electronics targeted for insertion in high temperature, extreme vibration, and corrosive media must satisfy a set of minimum reliability criteria before becoming acceptable for operational use.
Typically these devices operate in environments of 600° C. and above. This is very challenging since conventional semiconductor electronic and sensing devices are limited to operating in temperatures less than 300° C. due to the limitations imposed by material properties and packaging. Silicon carbide-based electronics and sensors have been demonstrated to operate in temperatures up to 1000° C. thereby offering promise of direct insertion into the high temperature environment.